function guid() {
    var s = [];
    var hexDigits = "0123456789abcdef";
    for (var i = 0; i < 36; i++) {
        s[i] = hexDigits.substr(Math.floor(Math.random() * 0x10), 1);
    }
    s[14] = "4"; // bits 12-15 of the time_hi_and_version field to 0010
    s[19] = hexDigits.substr((s[19] & 0x3) | 0x8, 1); // bits 6-7 of the clock_seq_hi_and_reserved to 01
    s[8] = s[13] = s[18] = s[23] = "-";

    var uuid = s.join("");
    return uuid;
}

var currentAlertId = null;

var alertify = {
    error: function (msg) {
        this.message("error",msg);
    },
    message: function (type,msg) {
        if(currentAlertId){
            let tag = document.getElementById(currentAlertId);
            if( tag ){
                document.body.removeChild(tag);
            }
        }
        let uuid = guid()
        const alert = document.createElement('div');
        alert.setAttribute("id", uuid);
        currentAlertId = uuid;
        alert.style.position="fixed";
        alert.style.maxHeight="50px";
        alert.style.maxWidth="200px";
        alert.style.padding="10px"
        if(type && type==='error'){
            alert.style.backgroundColor="red";
            alert.style.color="#FFF";
        }
        alert.style.marginLeft="auto";
        alert.style.marginRight="auto";
        alert.style.left="50%";
        alert.style.top="5%"
        alert.style.transform="translate(-50%, -50%)";
        alert.innerHTML="<span>"+msg+"</span>"
        document.body.appendChild(alert);
        setTimeout(function() {
            // 关闭
            let tag  = document.getElementById(currentAlertId);
            if(tag){
                document.body.removeChild(tag);
            }
        }, 2000);
    }
}